Anaesthesia
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Clinical Trial Controlled Clinical Trial
Circulatory effects of labetalol during halothane anaesthesia.
Labetalol is a drug possessing both alpha and beta adrenergic receptor blocking properties. Its possible use in induced hypotension during halothane anaesthesia has been investigated. It causes a satisfactory decrease in arterial pressure unaccompanied by tachycardia. ⋯ This reduction was associated with decreases in Qt of 18% and 12% respectively. In the presence of labetalol, with 3% halothane and spontaneous respiration, the depressant effects of the anaesthetic on the heart became rapidly apparent: Qt was reduced by a further 28%. In patients not receiving labetalol, the depressant effects of 3% halothane were frequently countered by the positive inotropic effects of hypercarbia.
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Clinical Trial Controlled Clinical Trial
Pain and clinical thrombophlebitis following intravenous diazepam and lorazepam.
Eighty-seven per cent of surgical patients receiving undiluted diazepam experienced pain on injection while 6-16%, depending on the dose, manifested evidence of clinical thrombophlebitis. This was improved when diazepam, 10 mg, was diluted to 20-40 ml with intravenous solution. In contrast, lorazepam appeared to have minimal irritative or injurious effects on veins whether undiluted or diluted. In view of these results and clinical studies reporting a higher patient acceptance of lorazepam than diazepam, lorazepam may be a superior drug for use in anaesthesia.
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A case of atrial fibrillation, with a fast ventricular response, which developed under enflurane anaesthesia is described in a patient previously treated with digitalis and propranolol. The intravenous administration of propranolol was ineffective whereas that of neostigmine and atropine, 2 hours later, was successful and reduced the ventricular rate to normal values.